“First time I hear from them and they open with threats. No attempt at a dialogue,” founder George Hotz writes in a tweet from the company’s account, including a PDF of the letter. “The comma one is canceled. comma.ai will be exploring other products and markets.”

The comma one is cancelled. comma.ai will be exploring other products and markets. Hello from Shenzhen, China. -GH 3/3

Hotz quick dismissal of the project under legal duress is a far cry from the confidence he demonstrated this summer when discussing the project with Inverse.

“We’re going to get 100,000 miles easily,” 26-year-old Hotz, who came to fame at 17 as the first person to jailbreak an iPhone, told Inverse in June. At the time, the company had only cataloged 5,000 of the 100,000 miles Hotz estimated it needed to launch the project on Amazon, but through its Chffr app that rewarded users for reporting data, the company had been quickly raking up miles.

A Comma.ai test car

The letter sent to Hotz included a special order requesting the company provide data on 15 different questions by November 10, or Hotz would be fined “civil penalties of up to $21,000 a day.”

“We are concerned that your product would put the safety of your customers and other road users at risk,” Paul Hemmersbaugh, chief counsel of the Department of Transportation wrote in the letter. We strongly encourage you to delay selling or deploying your product on the public roadways unless, and until, you can ensure it’s safe.”

Requests outlined in the special order included describing how the software would be installed in the vehicle, and the steps that company has “taken to ensure that installation of the comma one, in any supported vehicle, does not have unintended consequences on the vehicle’s operation.”

From the Comma.ai coloring app, which was used to develop the car's self-driving technology.

Scrapping the project, however, means that Comma.ai won’t have to pull together any data.

“Would much rather spend my life building amazing tech than dealing with regulators and lawyers. It isn’t worth it,” Hotz said in another tweet.

Would much rather spend my life building amazing tech than dealing with regulators and lawyers. It isn't worth it. -GH 2/3

In the letter, the NHTSA points out that it’s likely that some drivers will use the “product in a manner that exceeds its intended purposes.” The limitations of autonomous cars being misunderstood by drivers has caused increasing concern for companies like Tesla, which introduced new Autopilot safety warnings in August.

“The comma one will not turn your car into an autonomous vehicle. It is an advanced driver assistance system. To put it in traditional auto manufacturer terms, it is ‘lane keep assist’ and ‘adaptive cruise control,’” Comma.ai wrote in a blog posted a week before it was announced they would cease production on the kit.

Inverse has reached out to George Hotz for comment, and will update this story when we hear back.